This invention relates to a binocular display apparatus capable of providing a three-dimensional (3-D) image to an observer by use of right-eye and left-eye images having parallax.
In a visual display device or visual display system, various types of binocular displays which can display an image in a stereoscopic fashion are proposed.
FIG. 16 is an external perspective view showing a state wherein a head mounted display (HMD) 100 which is one example of a conventional binocular display of this type is used. The HMD 100 is one type of binocular display and is mounted on the head of an observer M such that a pair of left and right display units 101 each constructed by a display element and a magnifying optical system are respectively disposed in front of the left and right eyes of the observer M with the two end portions thereof supported by supporting frames 102. A head motion sensor 104 for detecting the motion of the head is mounted on a central portion of a coupling frame 103 which couples the other end portions of the supporting frames 102, that is, on a portion set on the top portion of the head.
On each of the supporting frames 102, an external connector 106 and headphones 107 for outputting a sound into the ears are mounted by a supporting member 105. The external connector 106 is connected to a portable data processor 120 by a connection cable 110. Operation buttons 121 are provided on the data processor 120 and the observer M selectively operates the operation buttons 121 so as to observe a desired image.
By operating the operation buttons 121 of the data processor 120, the left-eye image of the display unit is supplied to the left eye of the observer M and the right-eye image thereof is supplied to the right eye of the observer M so that the observer M can observe the 3-D image. At this time, since the 3-D image corresponds to the motion of the head detected by the head motion sensor 104 and is accompanied by a corresponding sound, the image can be observed with a natural sense.
In the binocular display such as the HMD 100, if the state of observation of a 3-D image by the binocular display is greatly different from the image pickup state of a 3-D video camera, it becomes difficult for the observer M to perform fusion of the images (image fusion), and as a result, the image may be observed as double images or as a 3-D image which is extremely unnatural. One concrete example of this problem is explained below.
As shown in FIG. 17A, when images 133 and 134 taken by two 3-D video cameras 131 and 132 disposed in parallel are observed by use of a binocular display 135, image-fusion cannot be attained without greatly inclining the left and right eyes of the observer M inwardly.
Further, as shown in FIG. 17B, when images 133 and 134 taken by two 3-D video cameras 131 and 132 disposed with the optical axes thereof inclined inwardly are observed by use of an HMD 136 having optical systems arranged in parallel, left and right images observed by left and right eyes IL and IR are subjected to fusion at the infinite point. In this case, the observer observes the image with an extremely unnatural sense.
As a means for solving the above problem, a means for controlling the parallax of a 3-D image as is disclosed in Jnp. Pat. Appln. KOKAI Publication No. 7-167633, for example, is proposed. The means disclosed in the above publication calculates the parallax of the left and right images or the three-dimensional position thereof and controls the parallax so as to reproduce the depth position of the image on the surface of the binocular display unit or at a specified distance by use of the result of calculation. Further, in the above publication, an example in which the parallax is controlled to reproduce the depth position of an image which the observer now wants to observe on the surface of the binocular display unit or at a specified distance by use of a line-of-sight detector is also disclosed.
The "parallax" indicates the amount of positional deviation between image portions in corresponding positions of the left and right images. Therefore, when the parallax is calculated, for example, it is necessary to detect an image portion included in the right image and corresponding to a specified image portion of the left image when attention is given to the specified image portion of the left image, detect the position of the detected specified image portion and then derive the amount of positional deviation between the left and right images.
The conventional apparatus having the above parallax control section has the following problem. That is, in the conventional apparatus, since it is necessary to detect corresponding specified image portions in the left and right images, the process cannot be started until all of the data items of one image plane of the left and right images are stored into the memory. Therefore, it is necessary to use a memory of large storage capacity. Further, there occurs a problem that image signals sequentially supplied cannot be processed on the real-time basis. The line of sight of the observer M may sometimes fluctuate while observing an image containing a close-range view and distant view, and in such a case, the amount of parallax to be controlled will greatly vary and a 3-D image cannot be stably observed.
An object of this invention is to provide a binocular display apparatus capable of easily and adequately providing a three-dimensional image which can be easily synthesized by the observer without particularly effecting the calculation for parallax and the like.